Rheostat.



UNITE .fw ys 'n maar onirica CHARLES A. CADWELL, OF CLEVELAND, OHIO, ASSIGNOR TO THE ELECTRIC RAILWAY `IIVIPLE',OVEIVIEIN'T COMPANY, 0F CLEVELAND, OHIO, A CORPORATION OF OHIO.

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Patented Jan. 7,' im '.fD.

Application filed May 10, 1917. Serial No. 137,685.

T all whom z'zf 'may concern Be it known that I, CHARLES A. CAnwnLL, A

l a citizen of the United States, and a resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented a new and useful Improvement in Rheostats, of which the fol-4 lowing isa specification, the principle of the invention bemg herein veriplamed and the best Inode in which I have contemplated applying that principle, so as to distinguish it from other inventions.

The presentimproved rheostatis designed for,use in connections which require the interposition of'a variable amount of resistance, and where such resistance may require to be considerable. At the same time it is desired that the rheostat beportable, so that it must not only be kept within reasonable compass, but also not be so heavy but that two men can carry the same. 'Io the accomplishment of the foregoingand related ends, said invention, then, consists of the means hereinafter fully described and particularly pointed out in the claims.

' The annexed drawing and the following description set forth in' detail certain mechanism embodying the invention, such disclosed I means constituting, however, but one of various mechanical forms in which the principle of the invention may be used.

In said annexedvdrawingz- Figure' l is a side elevationalxview of a rheostat embodying my present improvements, a portionof the wire screen which incloses the coils of the rheostat being sectioned away and the coils themselves being "in the main shown diagrammatically; 1g. 2 is a top plan view of the saine; Fig. 3 is alt-ransverse section of a detail, the plane of the sec- 40 tion being indicated by the line 3-3, F 1g. 2;

and Fig 4 is 'a diagrammatic view of the apl paratus. A

The resistance element, proper, consists ,of a spirally arranged helical coill of wire, 15 preferably of Monel metal, as oil'ering the greatest'resistance for a given cross-section. The several convolutions of' this coil, as clearly shown' in FigsA and 2, are arranged to engage with the inner faces of a plurality of parallel vertical standards joined at their respective upper and` lower ends by frames 2 of general oval shape, so as to surround al hollow space.

*These standards, in the preferred' form 56 illustrated, are built up, of central rods 3,

upon-which are mounted a series of insulator spools l held spaced from the end-frames 2, and from each other, by means of collars 5- of less diameter, which are preferably, although not necessarily, of insulating mate- 60 rial. The collars between the endmost spools and the adjacent frame are of varying lengths, so that the spools will be disposed in spiral fashion to properly receive and hold the convolu-tions of the resistance coil. The tension of the latter may be relied upon to hold the coils in contact with these spools, although provision may be made to tie them i thereto, at least in places, if desired. ASince the tendency, however, of the coil, when 70 heated, is to expand, itwill remain all the more securelyin place when current is actu'- ally being passed through the rheostat, in contradistinction to an arrangement where the convolutions ofthe coil surround the supporting standards, or other kind of frame.

In order to vary the amount of resistance inthe circuit a series of plug-sockets 6 is provided, each connected withthe coil l at a differ-ent point by branch conductors 7, so that by inserting the end ofthe one main lead 8 in one or the other of these sockets, a correspondingly greater or smaller resistance will be introduced in the circuit. T he form of the sockets is clearly shown in Fig. 3, and S5' for convenience they are disposed in a` linev across the Lipper frame 2, being' vembedded in suitable insulating material 9 held'between angle bars 10. Included in the coni nection from the other lead to the coil is an automatic switch l5 of the breaker type 'of handles 1l .are attached to the upper `frame 2 at rectanguiarly related points, such handles being thus attached topivots l2, that allow them to normally depend vertically alongside the apparatus. rl'ihe inner, shorter .100

ends 13 of the handles, however, are arranged to interlock with the bars 14, which provide specific means for their attachment to the frame, when such handles are raised into horizontal position, and, 'in the latter 10a position of the handles tW,o operators can readily carry the apparatus between them,

by each one grasping a pair of the handles. `Other modes of applying the principle of my invention may be employed instead of the one explained, ychange being made as regards the mechanism herein'disclosed, provided the means stated by any of the followingclaims or the equivalent of such stated means be employed.

l therefore particularly point out and distinctly claim as myinvention:-

l. In a device of the character described, the combination with a plurality of parallel insulating standards surrounding a holloav space, each of said standards comprising a central rod and a series of insulator spools mounted thereon.; of a helically arranged coil of resistance wire disposed in the space inside of said rods and contacting with said spools, so as to -be supported thereby, said spools being disposed in spiral fashion on said rods, substantially as described.

2. ln a device of the character described, the combination of end frames of general oval form; a plurality of parallel rods connecting said frames and so surrounding a hollow space; a series of insulator spools on each of said rods, the spools on successive rods being disposed in spiral fashion; and a helically arranged coil ot" resistance wire disposed in the space inside of said rods and contacting with said spools so as to be supported thereby.

In a device of the character described, thecombination with a plurality of parallel insulating standards surrounding a hollow space; ot a helically arranged coil of resist ancel Wire disposed inside of and contacting with said standards, so as to be supported thereby; and a plurality of contacts respectively connected with the ends'of said coil and at points intermediate of such ends, substantially as described.

Signed by me, this '-l day of May, 1917.

' CHARLES A.. CADWELL. 

